Gas turbine engine with pylon mounted accessory drive

ABSTRACT

A gas turbine engine includes an accessory gearbox within an engine pylori. The accessory components may be mounted within the engine pylori to save weight and space within the core nacelle as well as provide a relatively lower temperature operating environment.

BACKGROUND OF THE INVENTION

The present invention relates to a gas turbine engine pyloriarrangement.

Aircraft powered by gas turbine engines often include a mechanicallydriven accessory gearbox to drive accessory systems such as fuel pumps,scavenge pumps, electrical generators, hydraulic pumps, etc. The powerrequirements of the accessory gearbox continue to increase as the numberof electrical systems within aircraft increase.

Conventional gas turbine engine accessory gearboxes utilize a separategearbox case mountable underneath the engine axially near the diffusercase. The accessory gearbox is driven by an angle gearbox axiallyforward of the accessory gearbox through a layshaft. The angle gearboxis driven by a towershaft driven by the high-pressure spool.

Although effective, one disadvantage of this conventional arrangement isthe utilization of a relatively significant amount of space within theengine core nacelle as well as the multiple shaft and gearboxarrangement required to transfer power from the towershaft to theindependent accessory gearbox. To accommodate these design conditions,the nacelle design may provide less than optimal performance at cruiseconditions.

Accordingly, it is desirable to provide an accessory gearbox for a gasturbine engine which provides power to larger generators thanconventional engines, yet facilitates nacelle packaging.

SUMMARY OF THE INVENTION

The gas turbine engine according to one disclosed embodiment of thepresent invention locates an accessory gearbox within an engine pylori.The accessory gearbox includes a geartrain driven by at least onetowershaft arrangement driven by the core engine. The towershaftarrangement extends through the core nacelle and the fan nacelle intothe engine pylori. The geartrain facilitates direct drive of at leastone accessory component to provide a more optimized core nacelle. Theaccessory components may be mounted within the engine pylori to saveweight and space within the core nacelle and provide a relatively lowertemperature operating environment which increases geartrain andaccessory component life. This arrangement also frees up additionalspace within the core nacelle for other externals.

The present invention therefore provide an accessory gearbox for a gasturbine engine which provides power to larger generators thanconventional engines, yet facilitates nacelle packaging.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of this invention will becomeapparent to those skilled in the art from the following detaileddescription of the currently disclosed embodiment. The drawings thataccompany the detailed description can be briefly described as follows:

FIG. 1 is a general schematic sectional view through a gas turbineengine along the engine longitudinal axis; and

FIG. 2 is a general schematic view of pylori located accessory systems.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENT

FIG. 1 illustrates a general partial fragmentary schematic view of a gasturbine engine 10 suspended from an engine pylori P within an enginenacelle assembly N as is typical of an aircraft designed for subsonicoperation. The engine pylori P or other support structure is typicallymounted to an aircraft wing W (FIG. 2), however, the engine pylori P mayalternatively extend from other aircraft structure such as an aircraftempennage.

The turbofan engine 10 includes a core engine C within a core nacelle 12that houses a low spool 14 and high spool 24. The low spool 14 includesa low pressure compressor 16 and low pressure turbine 18. The low spool14 may drive a fan section 20 through a gear train 22. The high spool 24includes a high pressure compressor 26 and high pressure turbine 28. Acombustor 30 is arranged between the high pressure compressor 26 andhigh pressure turbine 28. The low and high spools 14, 24 rotate about anengine axis of rotation A.

The engine 10 in the disclosed embodiment is a high-bypass gearedarchitecture aircraft engine. In one disclosed embodiment, the engine 10bypass ratio is greater than ten (10:1), the turbofan diameter issignificantly larger than that of the low pressure compressor 16, andthe low pressure turbine 18 has a pressure ratio that is greater than5:1. The gear train 22 may be an epicycle gear train such as a planetarygear system or other gear system with a gear reduction ratio of greaterthan 2.5:1. It should be understood, however, that the above parametersare only exemplary of one embodiment of a geared architecture engine andthat the present invention is applicable to other gas turbine enginesincluding direct drive turbofans.

Airflow enters a fan nacelle 34, which at least partially surrounds thecore nacelle 12. The fan section 20 communicates airflow into the corenacelle 12 to power the low pressure compressor 16 and the high pressurecompressor 26. Core airflow compressed by the low pressure compressor 16and the high pressure compressor 26 is mixed with the fuel in thecombustor 30 and expanded over the high pressure turbine 28 and lowpressure turbine 18. The turbines 28, 18 are coupled for rotation with,respective, spools 24, 14 to rotationally drive the compressors 26, 16and, through the optional gear train 22, the fan section 20 in responseto the expansion. A core engine exhaust E exits the core nacelle 12through a core nozzle 42 defined between the core nacelle 12 and a tailcone 32.

The core nacelle 12 is at least partially supported within the fannacelle 34 by structure 36 often generically referred to as Fan ExitGuide Vanes (FEGVs), upper bifurcations, lower bifurcations or suchlike. A bypass flow path 40 is defined between the core nacelle 12 andthe fan nacelle 34. The engine 10 generates a high bypass flowarrangement with a bypass ratio in which approximately 80 percent of theairflow entering the fan nacelle 34 becomes bypass flow B. The bypassflow B communicates through the generally annular bypass flow path 40.

An accessory gearbox 60 mounted within the engine pylori P includes ageartrain 62 driven by at least one towershaft arrangement 64 whichtakes power off of the core engine C. The towershaft arrangement 64extends through either or both the core nacelle 12 and the fan nacelle34 into the engine pylori P. The towershaft arrangement 64 may include asingle towershaft which is in meshed engagement with either of the lowspool 14 or the high spool 24. Alternatively, the towershaft arrangement64 may include two towershafts, one of each in meshed engagement withthe respective low spool 14 and the high spool 24.

The accessory gearbox 60 supports the geartrain 62 to facilitate directdrive of at least one accessory component 66 and therefore provide amore optimized core nacelle 12. The geartrain 62 drives each auxiliaryengine component at the proper speed. The geartrain 62 provides power topumps, electrical generators and various other systems. The accessorycomponents 66 may be mounted within the engine pylori P and includecomponents such as a starter/generator SG, a deoiler D, a hydraulic pumpHP, an oil pump OP, a fuel pump FP, a generator G and such like (FIG. 2)which thereby saves weight and space within the core nacelle 12.Location of the accessory components 66 within the pylori also providesa relatively lower temperature environment to thereby increase geartrain62 and accessory component life.

It should be understood that any number and type of accessory components66 are usable with the present invention. Furthermore, accessorycomponents may alternatively, or in addition, be located in other areassuch as in the wing W, core nacelle, fuselage, etc. Optimization of thecore nacelle 12 increases the overall propulsion system efficiency tothereby, for example, compensate for the additional weight of theextended length towershaft. This arrangement also frees up additionalspace within the core nacelle below the engine case structure for otherexternals and accessory components.

It should be understood that relative positional terms such as“forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like arewith reference to the normal operational attitude of the vehicle andshould not be considered otherwise limiting.

The foregoing description is exemplary rather than defined by thelimitations within. Many modifications and variations of the presentinvention are possible in light of the above teachings. The disclosedembodiments of this invention have been disclosed, however, one ofordinary skill in the art would recognize that certain modificationswould come within the scope of this invention. It is, therefore, to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described. For thatreason the following claims should be studied to determine the truescope and content of this invention.

1. An engine pylori assembly for a gas turbine engine comprising: anengine pylori; and an accessory gearbox mounted within said enginepylori.
 2. The assembly as recited in claim 1, wherein said accessorygearbox includes a geartrain.
 3. The assembly as recited in claim 2,wherein said geartrain drives at least one accessory component.
 4. Theassembly as recited in claim 3, wherein said at least one accessorycomponent includes a starter/generator.
 5. The assembly as recited inclaim 3, wherein said at least one accessory component includes adeoiler.
 6. The assembly as recited in claim 3, wherein said at leastone accessory component includes a hydraulic pump.
 7. The assembly asrecited in claim 3, wherein said at least one accessory componentincludes a fuel pump.
 8. The assembly as recited in claim 3, whereinsaid at least one accessory component includes a generator.
 9. Theassembly as recited in claim 2, wherein said geartrain drives at leastone accessory component mounted within said engine pylori.
 10. Theassembly as recited in claim 9, wherein said at least one accessorycomponent includes a starter/generator.
 11. The assembly as recited inclaim 9, wherein said at least one accessory component includes adeoiler.
 12. The assembly as recited in claim 9, wherein said at leastone accessory component includes a hydraulic pump.
 13. The assembly asrecited in claim 9, wherein said at least one accessory componentincludes a fuel pump.
 14. The assembly as recited in claim 9, whereinsaid at least one accessory component includes a generator.
 15. Theintermediate case as recited in claim 1, further comprising at least onetowershaft which extends from said accessory gearbox through said enginepylori.
 16. A gas turbine engine system comprising: an engine pylori; anaccessory gearbox mounted within said engine pylon a towershaft drivenby one of a low pressure spool and a high pressure spool; and anaccessory gearbox mounted within said engine pylori, said accessorygearbox driven by said towershaft.
 17. The gas turbine engine as recitedin claim 16, wherein said accessory gearbox powers at least oneaccessory component.
 18. The gas turbine engine as recited in claim 16,wherein said accessory gearbox includes a geartrain which drives atleast one accessory component.
 19. The gas turbine engine as recited inclaim 16, wherein said accessory gearbox includes a geartrain whichdrives at least one accessory component, said at least one accessorycomponent mounted within said engine pylori.
 20. A method of driving anengine accessory component comprising the steps of: (A) extending atowershaft from a core engine at least partially into an engine pylori;(B) driving an accessory gearbox mounted within the engine pylori withthe towershaft; and (C) driving at least one accessory component throughsaid accessory gearbox.
 21. A method as recited in claim 19, whereinsaid step (A) further comprises: (a) driving the towershaft by a highpressure spool.